Artificial limb with an expansible foam stump socket



July 14, 1910 c. L. WELLINGTON ARTIFICIAL LIMB WITH AN EXPANSIBLE FOAMSTUMP SOCKET Filed Nov. 29, 1967 JNVENTOR CHARLES L. WELLINGTON 6 Y- Q iZTTORNEfiS United States Patent 3,520,002 ARTIFICIAL LIMB WITH ANEXPANSIBLE FOAM STUMP SOCKET Charles L. Wellington, 1228 Orion St.,Metairie, La. 70005 Filed Nov. 29, 1967, Ser. No. 686,502 Int. Cl. A61f1/02 US. Cl. 319 2 Claims ABSTRACT OF THE DISCLOSURE An artificial limbhaving a rigid outer shell defining a cavity for receiving a limb stump.A stump socket is carried in the cavity and includes flexible padspositioned adjacent the inner wall of the outer shell of the artificiallimb. An expansible foam material is inserted in the cavity in a liquidstate, and is capable of expanding into a substantially rigid cellularsupporting foam structure. An elastomeric member is positioned on thepatients limb stump in a stretched state for emphasizing scar tissue andbony areas of the limb. The limb stump is inserted within the socketprior to the expandible polymer expanding so that when such expands arigid cellular supporting structure is produced having a cavity with aninner wall complementary in shape to the limb stump.

This invention relates to artificial limbs, and more particularly to asupporting stump socket for the artificial limb.

Heretofore, stump sockets for artificial limbs have been constructed ofvarious materials. Canvas and stitched leather sockets were used formany years. However, such were not satisfactory since they often causedchafing and were not always comfortable due to the difficulty inproperly fitting the socket for a particular patients use. Attempts havebeen made to produce limb sockets which were complementary in shape tothe patients limb stump by first making a plaster of Paris stump whichcorresponded to the limb stump. A flexible socket was usually made usingsuch a plaster mold in order to produce a closely fitting andcomfortable socket. One such method similar to this is disclosed in theRyan Pat. No. 2,578,019 granted on Dec. 11, 1951. One of the problemsencountered in first making a plaster of Paris mold is that the limbstump normally changes shape when mounted in an artificial leg due tothe pressure exerted thereon, thus resulting in a poorly fitting anduncomfortable artificial limb.

Limb stumps constructed in accordance with the present inventionminimizes the above-mentioned problems, since in forming the stumpsocket an elastomeric member is placed on the limb stump in a stretchedstate so as to emphasize scar tissue and bony areas on the stump whichare normally the most sensitive areas thereon.

Accordingly, it is an important object of this invention to provide anartificial leg having a stump socket which minimizes the above-mentionedproblems.

Another important object of the present invention is to provide a stumpsocket for an artificial leg which is closely fitting and comfortablefor the patient.

Still another important object of the present invention is to provide anartificial limb with a stump socket which is easy and quick toconstruct, while conforming to the exact shape of the limb stump.

Still another important object of the present invention is to provide astump socket which distributes pressure on the stump of the patient in amanner which minimizes chafing and soreness.

The construction designed to carry out the invention will be hereinafterdescribed, together with other features thereof.

3,520,002 Patented July 14, 1970 The invention will be more readilyunderstood from a reading of the following specification, and byreference to the accompanying drawing forming a part thereof, wherein anexample of the invention is shown and wherein:

FIG. 1 is an elevational view, partially in section, of an artificialleg showing the stump socket.

FIG. 2 is an elevational view, partially in section, of an artificialleg constructed in accordance with the present invention having amodified base portion, and

FIG. 3 is an elevational view illustrating the manner in which the limbstump is prepared prior to making the socket for the artificial leg.

The drawing illustrates an artificial limb having a rigid outer shell Awhich defines a cavity for receiving a limb stump B. A stump socket iscarried in the cavity A and includes flexible pads C positioned adjacentthe inner wall of the outer shell of the artificial limb. An expansiblepolymer is inserted in the cavity in a liquid state, and is capable ofexpanding into a substantially rigid cellular supporting foam structureD. A form generally having an external shape corresponding to the shapeof the limb stump B is positioned in the cavity prior to the polymerexpanding. Thus, as the polymer expands a substantially rigid cellularsupporting structure is produced having a cavity with an inner wallcomplementary in shape to the form for providing a closely fittingcomfortable stump socket. The rigid cellular supporting structure isreinforced by the flexible pads C.

One of the most difiicult problems associated with an artificial leg isacquiring a good comfortable fit between the limb stump and the socketwhich receives such. Heretofore, as previously mentioned, plaster ofParis casts were used in forming the stump socket and pads were used tomake such fit properly. The disadvantage to this method is that it isimpossible to judge exactly what size padding, and where such should beapplied.

The outer shell A of the artificial leg may be constructed from anysuitable material, such as metal, extruded plastic, etc., and has a footportion 10 hinged to the bottom thereof in any suitable conventionalmanner. The outer shell A defines a cavity, the lower end of which isclosed by any suitable means. In FIG. 1 the lower end of the cavity isshown as being closed with a wooden base 11, while in FIG. 2 the lowerend of the cavity is filled with a hard solid material 12, such aspolyester resin, or any suitable light plastic substance. Another layerof light hard plastic material 13 is positioned on top of the solidmaterial 12 and extends upwardly in the cavity to a point approximately2 to 3" below where the bottom portion of the limb stump would normallyextend Within the cavity. After the lower end of the cavity is closedthe artifiical leg is ready to be equipped with the stump socket.

First, flexible pads C which may be constructed of any suitablematerial, such as flexible polyurethane, are positioned on the innerwall of the outer shell A. These pads may be of any suitable shape,however, they are shown in FIGS. 1 and 2 as being ring-shape padsadhered by any suitable means to the outer shell A. The patient for whomthe artificial limb is being prepared then places a very light stumpsock /z ply) on his limb stump B. An elastomeric sleeve member 15 ispulled over the stump sock 14 in a stretched state so as to emphasizethe contour of the limb stump. Such an elastomeric member may be a latexrubber sleeve with one end closed. By stretching the elastomeric memberover the limb stump such causes the limb stump to assume a contour whichcorresponds to the contour of the limb stump when such is positionedunder pressure in the artificial leg.

Thus, the rubber or elastomeric sleeve 15 must be quite tight so as -toserve the purpose of forming the stump into the shape that it assumes inthe prothesis under pressure.

The next step in the process of making the limb socket is thepreparation and application of the rigidcellular foam structure D. Onesuitable cellular foam used is manufactured by Cooke Paint & VarnishCompany of Kansas City, Mo., and is referred to as C Foam System #460.This polyurethane foam can be mixed in small quantities in a fluidstate. After the polyurethane foam has been mixed such is placed on topof the base enclosures 11 or 13. The patient then inserts the stumpwithin the socket and remains erect for approximately fifteen to twentyminutes in order to get the proper angle between the stump and thecasing A to assure proper positioning for walking. For the convenienceof the patient not having experience with this process, it is sometimesnecessary to form a jig which will allow the patient to remain seatedand still give the proper angle. When a new limb is being made, thestump B can be positioned centrally within the cavity, and anyvariations needed can be achieved with alignment screws.

The stump is left in the artificial leg until the foam has risen toencompass the limb stump and set enough so that the elastomeric member15 begins to free itself from the form, usually fifteen to twentyminutes. The stump is then removed from the elastomeric member 15leaving such inside the stump socket temporarily. The prothesis isallowed to set overnight at a temperature of approximately 80Fahrenheit. After the prothesis has set, the elastomeric member is thenremoved and the cavity formed in the stump stocket is the complement ofthe patients limb stump B and provides a closely fitting and comfortablestump socket. During forming of the cellular socket a polyethylene sheetis wrapped around the outer shell A for preventing the foam fromoverflowing onto the outer shell A.

The flexible foam pads C strengthens the rigid foam and provides asturdy and durable stump socket. Sometimes, in order to protect the scarand bony areas it is necessary to hollow out the foam adjacent theseareas a small amount during the fitting stage. One particular advantageof using the foam is that if the limb stump changes shape a new stumpsocket can be made without discarding the entire artificial limb. Thestump socket constructed in accordance with the present inventionrequires no liners or inserts in order to properly fit the limb stumptherein. It is noted that the rear portion 16 adjacent the top of theouter shell A is flared outwardly so as to permit the patient to bendhis leg at the knee joint freely. After the artificial limb has beenfitted to the patient and any modifications completed, a light coat ortwo of polyester resin or other suitable wearable plastic coating isplaced over the upper three or four inches of the foam in order to givesuch a hard smooth surface for better wear. Some of the advantages ofusing polyurethane cellular foam is that it is non-toxic, odorless, hassufiicient strength and hardness for support,

can be easily removed and new foam put in the same place if necessarydue to changes in the stumps shape, allows passage of air, absorbs smallamounts of moisture from perspiration, is resistant to normal acids, isselfextinguishing in regard to fire, and is lightweight.

In one particular artificial leg the flexible polyurethane foam pads areapproximately /8" in thickness. During the foaming operation of thecellular structure D heat will be generated, however, if thepolyurethane is prepared properly, such is not uncomfortable during thefitting operation.

The stump socket constructed in accordance with the present inventioneliminates the time-consuming step of first producing a plaster of Parismold which frequently is not the same shape of the limb stump when suchis under pressure. The artificial limb may be attached to the patientsthigh by any suitable attachment.

What is claimed is:

1. An artificial limb having a rigid outer shell, a stump socket carriedin said shell, said socket including flexible pads carried adjacent andin contact with an inner wall of said outer shell of said artificiallimb, a substantially rigid cellular structure carried in a closelyfitting relationship in said outer shell, said rigid cellular structureencompassing said flexible pads, and said pads being substantially lessrigid than said cellular structure for providing a reinforced cellularsupporting structure, and said cellular structure having a cavitytherein with an inner wall complementary in shape with the users limbstump.

2. The stump socket set forth in claim 1, wherein an upper portion ofsaid cellular supporting structure is coated with a layer of smoothplastic coating for adding wearability thereto.

References Cited UNITED STATES PATENTS 2,578,019 12/1951 Ryan 3l92,947,307 8/1960 Hoppe 128-90 3,035,280 5/1962 Hacklander.

3,309,714 3/1967 Porten 320 3,377,416 4/1968 Kandel 3l9 XR OTHERREFERENCES Plastic Appliances Moulded Direct to Patient by J. B.Brennan, The Lancet, Apr. 23, 1955, pp. 841-844.

Orthopaedic Appliances Atlas by J. W. Edwards, volume 2, ArtificialLimbs, Ann Arbor, Mich., 1960, pp. 274277 relied upon. Copy in Group335.

RICHARD A. GAUDET, Primary Examiner R. L. FRINKS, Assistant Examiner US.Cl. X.R. 26446, 222

